SUMMARY Fluorescence in situ hybridization is a molecular cytogenetic technique that localizes segments of DNA within tumor cells by using dyes that are visible with a fluorescent microscope. The technique has proved useful in typing a variety of tumors such as oligodendrogliomas and in understanding the genetic forces driving oncogenesis.

Fluorescent in situ hybridization is the standard method for visualizing the spatial distribution of RNA. Although traditional histochemical RNA detection methods suffered from limitations in resolution or sensitivity, the recent development of peroxidase-mediated tyramide signal amplification provides strikingly enhanced sensitivity and subcellular resolution. In this chapter, we describe opti...

Fluorescent in situ hybridization (FISH) techniques are becoming extremely sensitive, to the point where individual RNA or DNA molecules can be detected with small probes. At this level of sensitivity, the elimination of 'off-target' hybridization is of crucial importance, but typical probes used for RNA and DNA FISH contain sequences repeated elsewhere in the genome. We find that very short (e...

We have studied human spermatozoa from 24 normal, healthy unexposed men, 18 of whom were semen donors at the Sperm Bank in Turku, using multicolor fluorescence in situ hybridization with two chromosome-specific probes. The possible age-related increase in aneuploidy frequencies was assessed. Ten thousand spermatozoa were scored per individual for the presence of hyperploid, i.e., disomic and di...

Progressive telomere shortening occurs with division of normal human cells, and eventually leads to replicative senescence. The mechanism by which the shortened telomeres cause growth arrest is largely unknown. Transcriptional silencing of genes adjacent to telomeres, also called telomere position effect, has been hypothesized as a possible mechanism of telomere-mediated senescence. However, th...

Fluorescence in situ hybridization on extended DNA (fiber-FISH) is a powerful tool in high-resolution physical mapping. To introduce this technique into cotton, we developed the technique and tested it by deliberately mapping of telomere and 5S rDNA. Results showed that telomere-length ranged from 0.80 kb to 37.86 kb in three species, G. hirsutum, G. herbaceum and G. arboreum. However, most of ...

Targeting of DNA molecules to specific subcellular positions is essential for efficient segregation, but the mechanisms underlying these processes are poorly understood. In Escherichia coli, several plasmids belonging to different incompatibility groups (F, P1 and RK2) localize preferentially near the midcell and quartercell positions. Here we compare the relative positions of these three plasm...